X-ray microscopy is typically performed in synchrotrons. Synchrotrons are a good source for X-ray radiation. They produce spectrally pure, powerful, and highly collimated beams.
X-ray radiation has many advantages for imaging. The short wavelength enables very high resolutions. The penetrating nature of X-ray radiation enables the imaging of internal structures in semiconductor devices, for example. This characteristic can be very useful in the assessment of fabrication processes, for example.
Unfortunately, these synchrotrons are not available to many commercial institutions because of limited access to beam lines. Furthermore, the condensers used for the synchrotron-based x-ray microscopes typically have either a limited efficiency or inadequate imaging properties.
Laboratory sources are another option. These devices are typically based on electron bombardment of a target. Here, however, highly efficient optical trains are required to concentrate the weaker, diverging beams from these devices.
Various systems exist for concentrating X-ray radiation. Often, elliptical reflective surfaces are used. A source is located at one focal point of the ellipsis, defined by the surface, and the object of interest is located at the other focal point. Many times, these are off-axis devices making alignment difficult since the elliptical surface must be angularly and positionally aligned to an otherwise arbitrary position off of the optical axis.
Capillary tube concentrators have also been described in the prior art for concentrating X-ray radiation. These, in some cases, are manufactured by the mandrel method, in which a metal bar is selectively etched and then glass coated. Subsequently, the metal bar is removed. Often, these concentrators are either conically or elliptically shaped. They are used typically to collimate the light from a point X-ray source.